1. Field of the Invention
The present invention relates to coupling mechanisms, and more specifically to quick disconnect mechanical couplings.
2. Description of the Prior Art
Quick connect/disconnect mechanical couplings are connecting devices which permit easy, immediate connection and separation of fluid lines and electrical conductors. Typically, mechanical couplings are made up of two members commonly referred to as a male or pin connector and a female or socket connector.
Mechanical fluid couplings are typically designed to provide rapid coupling and uncoupling of high pressure lines while at the same time providing a high degree of safety during both flow and non-flow conditions. It is important that the fluid coupling assures positive locking and a fluid-tight joint in the high pressure line. The mechanical fluid couplings are generally designed to assist in overcoming the resistive forces of joining the coupling members resulting from the fluid pressure in the lines.
A common fluid coupling designed to assist in joining the coupling connectors is the threaded coupling having a threaded coupling nut which is captured by a shoulder and a retaining ring on a first coupling connector. A second coupling connector has an externally threaded portion. As the coupling nut is threaded on the externally threaded portion of the second coupling connector, the coupling nut acts against the shoulder of the first coupling connector drawing the coupling connectors together. The same principle is used with dogs or lugs to engage camming surfaces within a locking sleeve of a coupling connector. There is also the bayonet coupling whereby dogs or lugs fixed to one coupling connector react against a cam surface on the other coupling connector as one member is rotated relative to the other. One good feature of threaded couplings is that they are not likely to disconnect accidentally.
A non-threaded type coupling is a push style mechanical coupling which involves the displacement of a spring-loaded sleeve. The displacement of the spring-loaded sleeve allows locking members to move radially outward as the pin is inserted into the socket. Once the pin is fully engaged, the spring-loaded sleeve is released. As the spring-loaded sleeve returns to its normal position, an interior cam surface forces and holds the locking members in the pin's groove, thereby locking the pin within the socket. Unlocking involves the reverse process. The locking members can be balls, pins, palls, wire rings, dogs, cams, collets, breech lugs, etc.
Electrical couplings do encounter the resistive forces of fluid couplings. However, electrical couplings must be sealed and polarized to ensure the proper coupling of the electrical conductors. Conventionally, electrical couplings achieve their polarization by an external-internal key and keyway usually in the proximity of the contacts. Sealing of the contact cavity is typically achieved by O-ring seal glands located in this same region. In order to achieve proper and timely key engagement and seal engagement without one interfering with the other, the coupling usually requires additional length of engagement and stepped diameters, thus increasing the complexity of the connector and thereby increasing manufacturing costs. The internal-external relationship of key and keyway results in one internal element being hidden from view while the other external element is obscured by the coupling ring. Inspection of the face of each connector will allow an approximate orientation of connectors prior to coupling, but indexing is strictly by feel upon engaging connectors, since the key and keyway are obscured. Obscure O-ring seal glands often result in failure of the coupling as a result of the seal glands not being properly in place or defective.
Threaded coupling arrangements are used extensively in mechanically coupled electrical connectors. The mechanical advantage as well as the relative unlimited travel make it a favorite in most applications over other types of couplings, such as lever or bayonet-type couplings. To perform as intended, it is necessary that the screw threads have proper maintenance such as protection, thread cleaning, and lubrication. The problems inherent with conventional threaded coupling arrangements are cross threading and thread galling. Cross threading may occur if the coupling members are not properly oriented and aligned when starting to engage the threads. Thread galling is the result of a contamination or burr being ground into the thread, creating a high stress or hot spot. This usually occurs on new parts being mated the first time. Conventional connectors are not necessarily sold as mated pairs and are therefore subject to being mated in the field for the first time. Additionally, a substantial reduction in efficiency and mechanical advantage results from resistance to thread make-up due to friction caused by corrosion, contamination, or improper lubrication. Conventional threaded couplers often are difficult to uncouple when the connectors have been made-up for an extended period of time in a hostile environment. Additionally, conventional connectors may suffer mashed, gouged, or bruised threads which may destroy the usefulness of the coupling connector.
It is desirable to have a mechanical coupling providing the advantages of a threaded connection without the problems associated with the maintenance, protection, and lubrication of the threads. It is further desirable that the mechanical coupling have threads which are protected from damage and eliminate the possibility of cross threading and thread galling. Furthermore, the mechanical coupling should be adaptable for use in both fluid and electrical connections.